The present invention relates to sharpening of digital images and video for presentation on a display.
The resolution of a typical liquid crystal display is approximately 1920×1080 which is on the order of standard definition television. The resolution of a typical very high resolution diagonal display may be 4096×2160 or 3840×2160, and typically has viewing distances that are less than 2 picture heights. In order to display an image on a display in an aesthetically pleasing manner sharpening of the image is typically performed. The lack of sharpness typically results from imperfections in the captures process and/or loss of details due to image compression. However, sharpening of the image tends to result in annoying artifacts.
The traditional approaches to sharpening, such as using an unsharp mask, generally result in the introduction of visible degradation into the image being sharpened. The visual degradation is primarily due to enhancing the high frequency components and noise that often dominates the high frequency bands of an image. To moderate the enhancement of the visible degradation of the image, the amount of sharpening performed is controlled.
It is desirable to increase the sharpness of the image content while at the same time suppressing the noise in the resulting image.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.